Remark 3 Different from [1]} and [2]}, we do not assume the symmetry of \(W\) . Consequently, W can not only be satisfied by undigraphs, but also digraphs that permit doubly stochastic weight matrices, which is the reason we use the digraph to model the communication topology. On the converse, the communication topology can only be modeled by an undigraph in [1]} and [2]}, due to the symmetry of \(W\) .

